1. Technical Field
The present invention relates to a vehicle occupant restraint system. In particular, the present invention relates to an energy management device for seat belt webbing used in a seat belt system.
2. Description of the Prior Art
Seat belt systems are commonly used to restrain vehicle occupants. A typical seat belt system for a vehicle occupant includes a length of belt webbing extensible about the occupant and anchored to the vehicle. In the event of sudden deceleration such as occurs in a vehicle collision, the occupant continues to move forward relative to the vehicle and is restrained by the belt webbing.
The vehicle occupant can experience a sudden load if the occupant's forward movement is restrained by an inextensible length of belt webbing. To alleviate this sudden load, it is known to stitch together portions of the belt webbing. When the occupant engages the belt webbing with sufficient force, the load on the belt webbing tears the stitching. The tearing action produces a reduced force in the webbing as compared to a system without the tear stitching. The belt webbing portions separate producing a resistive force, and the belt webbing extends. Thus, the occupant's movement is restrained at a reduced rate over an increased period of time. This can reduce the abruptness of the load experienced by the vehicle occupant.